The present invention relates to a novel fluid pump mechanism which will deliver fluid or fluids at a given flow rate and with a greatly reduced pulsation. The present invention is particularly useful, although not limited, delivering liquid solvents at very high pressures.
For example, a typical liquid chromatographic column contains packing of finely divided particles for solute separation of a liquid sample. These packed columns create a very high back pressure on the fluid forcing means, i.e.: a positive displacement pump. Moreover, such a pump usually produces a pulsing flow due to the normal action of a piston within a chamber, which can distort the analysis of the solute.
Prior devices have employed pulse dampeners on the output side of the pump as well as dual pistons with overlapping cam methods to overcome such problems. Flow feedback and pressure feedback pumps have been used also. However, these mechanisms work inefficiently and are susceptible to breakdown because of the complexity of the components in their makeup. Such prior pumps still deliver pulsed flow because of chamber compliance compressibility of the fluid being pumped and other factors.
Moreover, constant speed motors driving single piston pumps will produce a pulsing flow and deliver reduced flow rate at high back pressures unless corrected. Additional components such as pressure transducers are expensive and necessarily add to the unreliability of the liquid solvent delivery system.
There is a need for a simple, reliable, metering pump which has greatly reduced pulsations in the delivery of fluids, especially liquid chromatographic solvents.